1. Field of the Invention
This invention relates to means and method for analyzing the presence of one liquid element or compound in another, different liquid element or compound. In one aspect, the invention relates to method and apparatus for continuously monitoring and controlling the amount of an immiscible liquid element or compound suspended in molten metal. In one aspect, the invention relates to a liquid contaminant sensor for molten metal, e.g., such as method and apparatus for continuously monitoring and controlling the amount of liquid magnesium chloride salts suspended in molten aluminum or aluminum alloys.
2. Background Information
Quality aluminum production requires monitoring and controlling the amount of contaminants or impurities in the aluminum or aluminum alloy. Whether the aluminum production is primary metal (from smelting alumina) or secondary (from recycling), quality aluminum production processes remove impurities such as sodium, calcium, hydrogen, and other trace elements, e.g., such as lithium. Quality aluminum processes require product aluminum containing not more than one part per million of sodium or calcium.
Conventional aluminum purification employs reaction gases to react with the impurities which are more electropositive than aluminum. Fluxing the aluminum or aluminum alloys with reaction gases such as chlorine is a first step in one method for removing hydrogen, sodium, calcium, or other trace elements. Fluxing with chlorine, sometimes called chloridizing, removes hydrogen by diffusion into the gas bubbles and forms contaminant salts of sodium chloride and calcium chloride.